issue22344.go

     1  // compile
     2  
     3  // Copyright 2019 The Go Authors. All rights reserved.
     4  // Use of this source code is governed by a BSD-style
     5  // license that can be found in the LICENSE file.
     6  
     7  // Test iota inside a function in a ConstSpec is accepted
     8  package main
     9  
    10  import (
    11  	"unsafe"
    12  )
    13  
    14  // iotas are usable inside closures in constant declarations (#22345)
    15  const (
    16  	_ = iota
    17  	_ = len([iota]byte{})
    18  	_ = unsafe.Sizeof(iota)
    19  	_ = unsafe.Sizeof(func() { _ = iota })
    20  	_ = unsafe.Sizeof(func() { var _ = iota })
    21  	_ = unsafe.Sizeof(func() { const _ = iota })
    22  	_ = unsafe.Sizeof(func() { type _ [iota]byte })
    23  	_ = unsafe.Sizeof(func() { func() int { return iota }() })
    24  )
    25  
    26  // verify inner and outer const declarations have distinct iotas
    27  const (
    28  	zero = iota
    29  	one  = iota
    30  	_    = unsafe.Sizeof(func() {
    31  		var x [iota]int // [2]int
    32  		var y [iota]int // [2]int
    33  		const (
    34  			Zero = iota
    35  			One
    36  			Two
    37  			_ = unsafe.Sizeof([iota - 1]int{} == x) // assert types are equal
    38  			_ = unsafe.Sizeof([iota - 2]int{} == y) // assert types are equal
    39  			_ = unsafe.Sizeof([Two]int{} == x)      // assert types are equal
    40  		)
    41  		var z [iota]int                  // [2]int
    42  		_ = unsafe.Sizeof([2]int{} == z) // assert types are equal
    43  	})
    44  	three = iota // the sequence continues
    45  )
    46  
    47  var _ [three]int = [3]int{} // assert 'three' has correct value
    48  
    49  func main() {
    50  
    51  	const (
    52  		_ = iota
    53  		_ = len([iota]byte{})
    54  		_ = unsafe.Sizeof(iota)
    55  		_ = unsafe.Sizeof(func() { _ = iota })
    56  		_ = unsafe.Sizeof(func() { var _ = iota })
    57  		_ = unsafe.Sizeof(func() { const _ = iota })
    58  		_ = unsafe.Sizeof(func() { type _ [iota]byte })
    59  		_ = unsafe.Sizeof(func() { func() int { return iota }() })
    60  	)
    61  
    62  	const (
    63  		zero = iota
    64  		one  = iota
    65  		_    = unsafe.Sizeof(func() {
    66  			var x [iota]int // [2]int
    67  			var y [iota]int // [2]int
    68  			const (
    69  				Zero = iota
    70  				One
    71  				Two
    72  				_ = unsafe.Sizeof([iota - 1]int{} == x) // assert types are equal
    73  				_ = unsafe.Sizeof([iota - 2]int{} == y) // assert types are equal
    74  				_ = unsafe.Sizeof([Two]int{} == x)      // assert types are equal
    75  			)
    76  			var z [iota]int                  // [2]int
    77  			_ = unsafe.Sizeof([2]int{} == z) // assert types are equal
    78  		})
    79  		three = iota // the sequence continues
    80  	)
    81  
    82  	var _ [three]int = [3]int{} // assert 'three' has correct value
    83  }
    84
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